narrator: this balancing act must take place in an environment that is more resilient than scientists once thought. ate pressures on t forestse tha: thgi th include further drying provoked by deforestatio by el niño, by global warming. they include extensive agriculture, which provides abundant sources of ignition for forests that are rendered flammable by drought or by logging. and all of those are coming together in an expanding frontier that's going to move up along the roads that are being paved into the heart of the world's largest rain forest. captioned by media access group at wgbh access.wgbh.org annenberg media ♪ for information about this and other annenberg media programs call 1-800-learner and visit us at www.learner.org.